Written by Antti Petaisto
on January 17, 2021

Making a GIF from a Video

There’s a lot of different ways to convert videos or images into a GIF, here’s a way that I found to work for my usecase, creating GIF’s to show steps of software applications. As with so much of what I do, I stand on the shoulder of giants who create the open source software that I use.

Get the Software

I use Ubuntu, so the steps I show for installing software are for it. Steps will be different for other OS’s. Once the requisite software the remaining steps should be the same.

sudo apt upgrade
sudo apt install ffmpeg 
sudo apt install imagemagick

You’ll also need Python, installation instructions for Python are here.

Video to Image Frames

We first need to convert our video into images. We’ll do this by using ffmpeg.

ffmpeg -ss 00:00 -i "$VIDEOLOCATION" -t "$VIDEOEND" "$IMAGEFILEDIRS"/%04d.png

The %04d.png will start at a file called 0001.png and increment up from there.

Grab a Subset of Image Frames

Depending on the frame rate we may have a lot of images. My video had a framerate of 30 frames per second and for a gif we don’t want that frequent of updates. I created a Python script to only grab the first 2 and the last 2 images as well as every 20th one. This reduces the number of images making for a much smaller files size.

import os
import shutil
import sys

# get input
image_location = sys.argv[1]
# determine directory location and set gif_file location
directory_location = image_location[0:image_location.rindex('/')]
gif_location = directory_location + '/gif_files/'
# create gif_location dir
if os.path.isdir(gif_location):
    shutil.rmtree(gif_location)
os.mkdir(gif_location)
print('image_location: ' + image_location)
directory = os.fsencode(image_location)
#count number of png image files in dir
num_pngs = len([name for name in os.listdir(image_location) if os.path.isfile(image_location + '/' + name) and name.endswith('.png') ])
print('num_pngs: ' + str(num_pngs))
    
# iterate through directory and grab first 2 and last 2 pngs as well as every 20th and copy to gif_files directory
for file in os.listdir(directory):
    filename = os.fsdecode(file)
    if filename.endswith(".png"): 
        filename_number = filename[:-4]
        if int(filename_number) % 20 == 0 or int(filename_number) in (1, 2, num_pngs, num_pngs-1):
           shutil.copy(image_location+ '/' + filename, gif_location + filename)

At some future date I plan to develop a more “intelligent” file_grabber that detects changes as well.

Convert to GIF

Once we have a subset of all the frame images we can convert it to a GIF. We’ll use ImageMagick to do this.

This converts the files in the gif_files directory to a gif with a 75ms delay.

convert -delay 75 -loop 0 "$VIDEODIR"/gif_files/*.png new_gif.gif

Putting all steps together

I used a bash script to put all the steps together. This allows me to run the script with a video as an input and output a GIF that’s much smaller than the raw output from ffmpeg

#!bin/bash

# inputs
VIDEOLOCATION=$1
VIDEOSTART=$2
VIDEOEND=$3

# getting dir
VIDEODIR=$(dirname "$VIDEOLOCATION")
echo $VIDEODIR
IMAGEFILEDIRS="$VIDEODIR"/image_files
GIFFILEDIRS="$VIDEODIR"/gif_files

# removing existing directorys and recreating
rm -rf "$IMAGEFILEDIRS"
mkdir "$IMAGEFILEDIRS"
echo $IMAGEFILEDIRS
rm -rf "$GIFFILEDIRS"
mkdir "$GIFFILEDIRS"
sudo chmod a+wrx "$IMAGEFILEDIRS"

# converting video to images
ffmpeg -ss 00:00 -i "$VIDEOLOCATION" -t "$VIDEOEND" "$IMAGEFILEDIRS"/%04d.png

# grabbing a subset of images
python3 /home/persamina/file_grabber.py $IMAGEFILEDIRS

# converting images into gifs
convert -delay 75 -loop 0 "$VIDEODIR"/gif_files/*.png new_gif.gif

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